Jet attrition in a fluidized bed. Part II: Effect of fluidized bed hydrodynamics

The effect of fluidized bed hydrodynamics on jet attrition with a supersonic attrition nozzle has been studied in this paper. The aim is to determine a hydrodynamic condition that can help improve particle attrition. Two hydrodynamic zones were created by a specially designed fluidized bed. Experiments were conducted with a supersonic attrition jet either straddling both hydrodynamic zones, or completely enclosed within one hydrodynamic zone. It is found that jet grinding is most effective when the nozzle tip is located in a high fluidization velocity region and jet tip located in a low fluidization velocity region. Also, a larger nozzle is more effective in terms of the new surface area created. A baffle is found to improve the jet attrition process when it was inserted underneath the jet tip cavity.

Effect of uneven fluidizing gas distribution and horizontal attrition nozzle penetration on new surface area created by jet attrition in a fluidized bedFigure optionsDownload as PowerPoint slideHighlights
► Jet grinding depends on local fluidized bed hydrodynamics.
► Jet grinding is better with nozzle tip in high fluidization velocity region.
► Jet grinding is better with jet tip in low fluidization velocity region.
► A larger nozzle is more effective for jet grinding.
► A baffle underneath the jet tip improves jet attrition.